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Seqirus Announces Late-Breaking Data at IDWeek 2020: New Real-World Evidence Shows Value of Adjuvanted Influenza Vaccine for Adults 65 Years and Older with Underlying Health Conditions


Seqirus, a global leader in influenza prevention, today announced new, late-breaking real-world evidence (RWE) to be presented at IDWeek 2020 indicating that an MF59®-adjuvanted trivalent seasonal influenza vaccine (aTIV) was more effective than standard, non-adjuvanted quadrivalent influenza vaccines (IIV4) in reducing influenza-related medical encounters in adults 65 years and older with at least one underlying health condition during the U.S. 2017/18 and 2018/19 influenza seasons. Non-statistically significant estimates precluded definitive conclusions for comparisons versus high-dose trivalent influenza vaccine (TIV-HD). Study results will be shared live as part of the late breaking oral presentation session on Saturday, October 24 at 10:00 am ET.[1]

“The data presented at IDWeek 2020 add to a consistent and growing body of evidence for the MF59®-adjuvanted seasonal influenza vaccine as an enhanced influenza vaccine for adults 65 years and older,” said Constantina Boikos, lead study author and Senior Manager, Center for Outcomes Research & Evaluation at Seqirus. “This represents one of the first times a large real-world, dataset integrating several sources of health information has been used to estimate relative vaccine effectiveness of an influenza vaccine over more than a single season, which allowed for the evaluation of an effectiveness outcome in a population typically not evaluated in randomized trials.”

Influenza causes significant morbidity and mortality in adults 65 years and older, as demonstrated by higher hospitalization and death rates in recent years, compared with young, healthy adults.[2] This population is subject to age-related immune decline, which can result in reduced immune response and in turn, reduced seasonal vaccine effectiveness.[3],[4] The MF59® adjuvant included in aTIV is designed to enhance the immune response to the influenza strains contained in the vaccine in adults 65 years and older.[5],[6],[7]

“At Seqirus we engage in scientific exchange with top infectious disease and influenza experts like those at IDWeek to build the body of seasonal influenza RWE, given the variable nature of the virus. This retrospective analysis underscores the importance of RWE to better understand how our influenza vaccines work in real-world settings,” said Gregg Sylvester, MD, Chief Medical Officer at Seqirus. “Amidst the ongoing COVID-19 pandemic, it’s more important than ever to help protect vulnerable populations, such as adults 65 years and older with comorbidities, through the use of seasonal influenza vaccines.”

The retrospective study was conducted using more than 3.8 million electronic medical records across both seasons linked to pharmacy and medical claims of U.S. adults 65 years with 1 health condition who received either aTIV, TIV-HD or standard egg-based quadrivalent influenza vaccine.1

This MF59®-adjuvanted seasonal influenza vaccine has an extensive clinical history, with 155+ million doses distributed over 20+ years* and licensure in 30 countries.[8] The quadrivalent formulation of the MF59® adjuvanted influenza vaccine, which contains an additional B strain to the trivalent formulation, was approved by the U.S. Food and Drug Administration (FDA) in February 2020 and is available for the 2020/21 influenza season.[9]

*Doses distributed globally as of September 2020, including both trivalent and quadrivalent formulations.8

About the Study

The objective of the study was to determine the relative vaccine effectiveness (rVE) of the MF59®-adjuvanted trivalent inactivated influenza vaccine (aTIV) compared to egg-derived standard quadrivalent inactivated influenza vaccines (IIV4) and high-dose trivalent inactivated influenza vaccine (TIV-HD) in preventing influenza-related medical encounters in older adults (65 years) with at least one comorbid health condition during the 2017-2018 and 2018-2019 influenza season.1

The retrospective study was conducted using more than 3.8 million electronic medical records linked to pharmacy and medical claims of U.S. adults 65 years with 1 health condition who received either aTIV, IIV4 or TIV-HD.1 Comorbidities included chronic pulmonary disease; asthma; myocardial infarction or congestive health failure; cerebrovascular disease or peripheral vascular disease; renal disease; diabetes (chronic or not chronic); any malignancy or metastatic solid tumors; HIV/AIDS; rheumatic disease; mild or severe liver disease.1

The primary outcome was influenza-related medical encounters in both the primary care and hospital settings.1 Adjusted odds ratios for age, sex, race, ethnicity, geographic region, comorbidities and weeks of vaccination were calculated for each health condition using inverse probability of treatment weighting.1 The rVE was determined using the formula (1-OR)*100 and reported with 95% confidence intervals (CI).1

Adjusted rVE indicated that older adults with underlying health conditions who received aTIV had statistically significant reductions in medical encounters compared to IIV4 for the 2017-2018 and 2018-2019 seasons.1 In the 2017-2018 season the adjusted rVE for adults with at least one health condition who received aTIV vs IIV4 was 7.1 (95% CI: 3.3, 10.8) for the 2017-2018 season and 20.4 (95% CI: 16.2, 24.4) for the 2018-2019 season.1 Non-statistically significant estimates precluded definitive conclusions for comparisons versus TIV-HD in reducing medical encounters for both seasons.1 For the 2017-2018 season, the adjusted VE of aTIV vs TIV-HD was -0.8 (95% CI: -8.9, 6.6) and 2.7 (95% CI: -2.7, 7.8) for the 2018-2019 season.1 Overall, the results of this study indicate the use of aTIV is more effective in reducing influenza-related medical encounters than standard quadrivalent seasonal influenza vaccines for adults 65 years with at least one healthcare condition.1

These results complement and are supportive of the primary analysis presented recently at the Annual Conference on Vaccinology Research (ACVR), hosted by the National Foundation for Infectious Diseases (NFID), that demonstrated aTIV to be more effective than standard influenza vaccines in preventing influenza-related healthcare encounters.[10]

A main limitation of this analysis is that the effectiveness outcome was not laboratory-confirmed influenza. However, results from a separate evaluation conducted within a larger population indicate alignment between influenza-related medical encounters and lab-confirmed influenza from CDC surveillance data. This supports the use of influenza-related medical encounters as defined in this study in Real World assessments of vaccine effectiveness. Furthermore, it must be acknowledged that estimates from observational studies may be impacted by residual confounding and bias, even after adjusting for confounding variables.1 

About Seasonal Influenza 

Influenza is a common, contagious seasonal respiratory disease that may cause severe illness and life-threatening complications in some people.[11] Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases, death.11 The CDC recommends annual vaccination for individuals aged 6 months and older, who do not have any contraindications.[12]Because transmission of influenza viruses to others may occur one day before symptoms develop and up to 5 to 7 days after becoming sick, the disease can be easily transmitted to others.11 Preliminary estimates from the CDC report that from October 1, 2019, through April 4, 2020, there were an estimated 410,000 to 740,000 influenza-related hospitalizations in the U.S.[13] Since it takes about two weeks after vaccination for antibodies to develop in the body that help protect against influenza virus infection, it is recommended that people get vaccinated before influenza begins spreading in their community.11 The CDC recommends that people get vaccinated by the end of October.[14] However, getting vaccinated too early (for example, in July or August), can be associated with reduced protection against influenza infection later in the flu season.14

About Seqirus

Seqirus is part of CSL Limited (ASX: CSL). As one of the largest influenza vaccine providers in the world, Seqirus is a major contributor to the prevention of influenza globally and a transcontinental partner in pandemic preparedness. With state-of-the-art production facilities in the U.S., the U.K. and Australia, and leading R&D capabilities, Seqirus utilizes egg, cell and adjuvant technologies to offer a broad portfolio of differentiated influenza vaccines in more than 20 countries around the world.

About CSL

CSL (ASX:CSL) is a leading global biotechnology company with a dynamic portfolio of life-saving medicines, including those that treat hemophilia and immune deficiencies, as well as vaccines to prevent influenza. Since our start in 1916, we have been driven by our promise to save lives using the latest technologies. Today, CSL — including our two businesses, CSL Behring and Seqirus - provides life-saving products to more than 70 countries and employs more than 27,000 people. Our unique combination of commercial strength, R&D focus and operational excellence enables us to identify, develop and deliver innovations so our patients can live life to the fullest. For more information about CSL Limited, visit

For more information visit and

Intended Audience

This press release is issued from Seqirus U.S. Inc. in Summit New Jersey, U.S. and is intended to provide information about our global business. Please be aware that information relating to the approval status and labels of approved Seqirus products may vary from country to country. Please consult your local regulatory authority on the approval status of Seqirus products.

Forward-Looking Statements

This press release may contain forward-looking statements, including statements regarding future results, performance or achievements. These statements involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements.

FLUAD® (Influenza Vaccine, Adjuvanted) and FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted)



What is FLUAD® (Influenza Vaccine, Adjuvanted) and FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted)?

FLUAD and FLUAD QUADRIVALENT are vaccines that help protect people aged 65 years and older from the flu. Vaccination with FLUAD or FLUAD QUADRIVALENT may not protect all people who receive the vaccine.

Who should not get FLUAD or FLUAD QUADRIVALENT?

You should not get FLUAD or FLUAD QUADRIVALENT if you have had a severe allergic reaction to any of the ingredients in the vaccine in the past, including egg protein, or a severe allergic reaction to a previous influenza vaccine.

Before receiving FLUAD or FLUAD QUADRIVALENT, tell your healthcare provider about all medical conditions, including if you:

  • have ever had Guillain-Barré syndrome (severe muscle weakness) within six weeks after getting a flu vaccine. The decision to give FLUAD or FLUAD QUADRIVALENT should be made by your healthcare provider, based on careful consideration of the potential benefits and risks.
  • have problems with your immune system or are taking certain medications that suppress your immune system, as these may reduce your immune response to the vaccine
  • have ever fainted when receiving a vaccine

What are the most common side effects of FLUAD and FLUAD QUADRIVALENT?

  • Pain or tenderness where the vaccine was given
  • Muscle aches
  • Headache
  • Fatigue

These are not all of the possible side effects of FLUAD or FLUAD QUADRIVALENT. You can ask your healthcare provider for more information.

What do I do if I have side effects?

Ask your healthcare provider for advice about any side effects that concern you.

To report SUSPECTED ADVERSE REACTIONS, contact Seqirus USA Inc. at 1‐844‐275‐ 2461 or VAERS at 1‐800‐822‐7967 or

You are also encouraged to report negative side effects of prescription drugs to the FDA. Visit, or call 1‐800‐FDA‐1088.

Before receiving this vaccine, please see the full US Prescribing Information for FLUAD or FLUAD QUADRIVALENT.

The information provided here does not include all that is known about FLUAD or FLUAD QUADRIVALENT. To learn more, talk about FLUAD with your healthcare provider.

FLUAD®, FLUAD® QUADRIVALENT, and MF59® are registered trademarks of Seqirus UK Limited or its affiliates.






Polina Miklush
+1 (908)

[1] Boikos, C. Fischer, L. O’Brien, D. et al. Relative Effectiveness of aIIV3 versus IIV4 and HD-IIV3 In Preventing Influenza-Related Medical Encounters in Adults ≥65 Years of Age at High Risk for Influenza Complications During the U.S. 2017-2018 and 2018-2019 Influenza Seasons. Presented at ID Week 2020.

[2] Centers for Disease Control and Prevention (CDC). (2019). People 65 years and Older & Influenza. Retrieved from: Accessed September 2020.

[3] Monto AS, Ansaldi F, Aspinall R, et al. (2009). Influenza control in the 21st century: Optimizing protection of older adults. Vaccine. 2009;27(37):5043-5053.

[4] McElhaney JE, Verschoor CP, Andrew MK, et al. (2020). The immune response to influenza in older humans: beyond immune senescence. BMC.

[5] Frey SE, Aplasca-De Los Reyes MR, Reynales H, et al. (2014). Comparison of the safety and immunogenicity of an MF59®-adjuvanted with a non-adjuvanted seasonal influenza vaccine in elderly subjects. Vaccine. 2014;32:5027-5034.

[6] O'Hagan DT, Ott GS, Nest GV, et al. (2013). The history of MF59® adjuvant: a phoenix that arose from the ashes. Expert Rev Vaccines. 2013;12(1):13-30.

[7] Banzhoff A, Pellegrini M, Del Giudice G, et al. (2008). MF59-adjuvanted vaccines for seasonal and pandemic influenza prophylaxis. Influenza Other Respir Viruses. 2008;2(6):243-24.

[8] Data on file. Seqirus Inc; 2019.

[9] FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted) [package insert]. Holly Springs, NC: Seqirus Inc; 2020.

[10] Boikos, C. Fischer, L. O’Brien, D. et al. Relative Effectiveness of aTIV Versus TIVe, QIVe and HD-TIV in Preventing Influenza-Related Medical Encounters During the 2017-18 and 2018-19 Influenza Seasons in the U.S. Presented at the Annual Conference on Vaccinology Research (ACVR).

[11] CDC. (2019). Key Facts about Influenza (Flu). Retrieved from: Accessed September 2020.

[12] CDC. (2020). Key Facts About Seasonal Flu Vaccine. Retrieved from: Accessed September 2020.

[13] CDC. (2020). 2019-2020 U.S. Flu season: Preliminary burden estimates. Retrieved from: Accessed September 2020.

[14] CDC. (2020). Who Needs a Flu Vaccine and When. Retrieved from: Accessed September 2020.